Means for draining moisture from steam in steam turbines



March .22, 1938. H. VAN TONGEREN ,1 3

MEANS FOR DRAINING MOISTURE FROM STEAM IN STEAM TURBINES Filed June 26,1956 FIGS FIE-3.4

Patented Mar. 22, 1938 UNITED STATES MEANS FOR DRAINING MOISTURE FRQMSTEAM IN STEAM TURBINES Hermannus van Tongeren, Heemstede, Netherlands 7Application June 26,

1936, Serial No. 87,566

In the Netherlands July 2, 1935 3 Claims.

This invention relates to means for draining moisture from steam insteam turbines.

It is well known that in steam turbines, and especially in the lowpressure stages thereof, part of the steam is condensed and that thewater of condensation thus formed has a deteriorating action on theblades. The principal object of my invention is an improved constructionwhereby the water droplets, which are thrown by centrifugal force fromthe rotor or rotors, are collected--and thereafter discharged from theoas ing-in such a manner that they cannot possibly return into theblading.

With this object in view, I suggest to provide a circumferentialgroovein the inner wall of the casing, said groove being so disposedrelative to the corresponding rotor that the droplets thrown radiallyoutwards from the rotor can reach the body of water already present inthe groove without contacting with any stationary part of the turbine.Since the body of water in the groove, owing to the impacts of thedroplets thrown thereinto, has a circumferential speed not essentiallysmaller than that of the droplets, the latter will be caught therebywithout considerable rebounding. It will easily be understood that sucha gyrating mass of water surrounding the rotor is much better adapted tocatch and hold the droplets than are stationary solid walls.

In order thatmy invention may be more fully understood by those skilledin the art, I shall now proceed to describe the same in further detailwith reference to the annexed drawing, in which:

Fig. 1 is part of an axial section of an axial flow turbine,

Fig. 2 shows part of a cross-sectional view of said turbine, along theline II--II in Fig. 1,

Figs. 3, 4 and 5 illustrate parts of axial sections along the linesIII--I1'I, IVIV and VV, respectively, in Fig. 2,

Fig. 6 shows a modification as part of an axial section of another axialflow turbine,

Fig. 7 is part of a cross-sectional view of said turbine, along the lineVIIVII in Fig. 6, and

Figs. 8, 9 and 10 are parts of axial sections along the lines VIIIVIII,IX--IX and X--X, respectively, in Fig. 7.

InFigs. 1-5, a rotary blade wheel is designated by I, the turbine casingby 2. The numerals 3 and 4 indicate normally shaped fixed guide bladerims on either side of wheel I. The butt strap or sealing ring 5 of themoving blades is provided, on the right hand side, i. e. on the outletside, with a drip rim or edge 6, from which the water droplets areradially thrown off. Surrounding said drip rim, the inner face of easing2 has a circumferential collecting groove I machined therein. As shown,the depth of said groove is greatest in the radial plane passing throughthe drip rim, i. e. on the outlet side of the moving blades, andgradually decreases towards the radial plane passing through the inletside of said blades. Through a small portion of the circumference, thesloping side wall of the groove 1 is recessed so as to form a sill II]located at a somewhat smaller distance from the turbine axis than thebottom of the groove. Secured to said sill as by screws 8a is a nozzle 8fitted at the inner end of a passage 9 provided in the wall of thecasing 2 and serving to discharge water collecting in the groove.

When the turbine is in operation, the groove I will after a certainperiod of time be filled with a gyrating, annular body of water, themore or less cylindrical inner surface of which will be substantiallyflush with the sill Ill. Any water flowing over said sill will be forcedby its kinetic energy into the nozzle 8 and thus be discharged throughthe passage 9.

Figs. 3, 4 and 5 clearly show that any droplet thrown radially off thedrip rim 6 will reach the level of the gyrating body of water in groove1 and thus be caught and held by said water, with out coming intocontact with the radial right hand side wall of said groove or with anyother stationary part of the casing.

It is not necessary to provide every rotor element traversed by more orless wet steam with a draining device as described. For instance, agroup of rotor elements or blade wheels, only the last wheel on theoutlet side of such group to gether with the part of the casingsurrounding such wheel may be provided with a draining device.

Figs. 6-10 of the drawing illustrate another embodiment of my invention,wherein the butt strap II is provided with two drip rims I2 and I3 onthe inlet and on the outlet side, respectively. Said drip rims aresurrounded by water collecting grooves I4 and I5, respectively, machinedin the turbine casing 2. Also in this case the depth of each groove isgreatest in the radial plane of the corresponding drip rim. The groovesare separated from one another by an annular ridge I6, which through asmall portion of its length is recessed to form a sill II, to which thenozzle 8 of the discharge passage 9 is secured by screws 8a.

Secured to the inner face of the ridge I6 is a flat ring l8, the sideedges of which are suitably spaced from the opposite radial walls of thegrooves 14 and I5, respectively, so that any droplets thrown from thedrip rims I2, I3 can freely pass through the narrow slots thus formedwithout coming into contact with said walls.

The strap l8 acts as a shield or baffie having for its effect greatly toreduce the circumferential speed of the steam carried along by the buttstrap I I. Owing thereto, the levels of the bodies of water in thegrooves I4, l5 are not seriously disturbed by wave motion.

What I claim is:

1. In a steam turbine, a casing, a rotor element provided with aradially directed drip rim, a circumferential water-collecting groove inthe inner wall of the casing situated in radial alignment of said driprim and with its bottom spaced from said rim and a water-dischargingconduit opening into said groove substantially level with said drip rim,the groove being so disposed and formed as to permit water dropletsthrown by centrifugal force from said drip rim to collect in said groovethus providing an annular body of water and to prevent said dropletsfrom being thrown into direct contact with any stationary solid Wall.

2. In a steam turbine, a casing, a rotor element provided with aradially directed drip rim, a circumferential water-collecting groove inthe inner wall of the casing situated in radial alignment of said driprim and with its bottom spaced from said rim and a water-dischargingconduit opening into said groove substantially level with said drip rim,the groove being so disposed and formed as to permit Water dropletsthrown by centrifugal force from said drip rim to collect in said groovethus providing an annular body of Water and to prevent said dropletsfrom being thrown into direct contact with any stationary solid wall,and an annular bafile secured to the casing partly closing said grooveleaving only a narrow circumferential slot in the radial plane of saiddrip rim.

3. In a steam turbine, a casing, a rotor element provided with a driprim at its inlet and outlet sides, a circumferential water-collectinggroove in the inner wall of the casing opposite the inlet and outletsides of said rotor element and in radial alignment with the respectivedrip rims, a circumferential ridge intermediate of said grooves, arecess in said ridge forming a sill and a Water-discharging conduitopening in said sill substantially level with the drip rims, the groovesbeing so dispose-d and formed as to permit water droplets thrown bycentrifugal force from the respective rims to collect in the respectivegrooves thus providing annular bodies of water in the bottoms of thegrooves, said droplets not coming in direct contact with any stationarysolid wall.

HERMANNUS VAN TONGEREN.

